Copyright by: The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, NY, all rights reserved.

General Description

The Dusky Grouse (until recently known as the Blue Grouse) is the largest of Montana's three species of mountain grouse. Both sexes have long, square tails which are unbarred. Males have slate-colored upper parts, white-based neck feathers around the air sacs, and yellow-orange eye combs. Females tend to be browner than males and have barring on the head, neck, and back. Both sexes have uniform blue-gray breasts and bellies, and feathered legs. Adult males range from 18.5 to 22.5 inches in length and 2.5 to 3 pounds in weight; adult females range from 17 to 19 inches in length and average about 2 pounds in weight.

Diagnostic Characteristics

Dusky Grouse are most likely to be confused with Spruce (Franklin) Grouse in Montana. Male Spruce Grouse, however, are considerably smaller than male Dusky Grouse and have a black breast patch. Female Spruce Grouse have white under parts with conspicuous black barring, while female Dusky Grouse are bluish-gray beneath.

(Records associated with a range of dates are excluded from time charts)

Habitat

Dusky Grouse winter at high elevations in conifer stands. In early spring, they descend to lower altitudes, where they prefer forest edges and openings. Broods may be found quite far from timber during summer and early fall. In the Bridger Mountains in early summer, broods were often observed in grass-forb areas (with arrow-leaf balsamroot being dominant); increased use of deciduous thickets was observed in late July to August (Mussehl 1958). See also Martinka 1970 for habitat comments from the Sapphire Mountains.

Ecological Systems Associated with this Species

Details on Creation and Suggested Uses and Limitations

How Associations Were Made
We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:

Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;

Examining the observation records for each species in the state-wide point database associated with each ecological system;

Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.

Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

Maxell, B.A. 2000. Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.

In winter they eat mainly conifer needles. In summer they eat a mixed diet of insects, green plants and berries. The young eat mainly insects (Mussehl 1971).

Ecology

Brood movement in summer is generally less than 0.5 mile. Brood break-up appeared concurrent with fall dispersal, in late August to early September and had lateral and altitudinal components. Brood range densities were 27 (1957) and 34 (1958) in a 1 square mile area (Mussehl 1958).

Reproductive Characteristics

Hatching dates in the Bridger Mountains ranged from May 25 to July 11, with the peak the 3rd week of June (Mussehl 1958). Near Fortine, hatching dates were June 10 to August 15; broods ranged from 1 to 10 young.

Montana Dept. of State Lands, 1978, Preliminary environmental review for the proposed granting of an underground mining permit to Beartooth Coal Company, Incorporated, for the reopening of an underground coal mine in the area of Bearcreek, Carbon County, Montana. July 10, 1978.

Citation for data on this website:Dusky Grouse — Dendragapus obscurus. Montana Field Guide. Montana Natural Heritage Program and Montana Fish, Wildlife and Parks. Retrieved on March 3, 2015, from http://FieldGuide.mt.gov/speciesDetail.aspx?elcode=ABNLC09020